This invention relates to data protection for a storage system.
Recent years have seen strengthening of regulations which oblige companies to keep business documents or the like for a long time. A function of preventing erasing or changing of data is required for a storage system which stores data such as business documents. To meet such a requirement, a storage system equipped with a WORM function (Write Once Read Many: updating prohibition function) has been provided (e.g., see EMC Corporation, “EMC Centera”, [online], [searched on May 28, 2004], Internet <URL: http://www.emc.com/pdf/products/centera/centera_guide.pdf>, and Network Appliance, “NetApp NearStore”, [online], [searched on May 28, 2004], Internet <URL: http://www.netapp.com/products/nearstore/>). The storage system having such a WORM function stores data to which a WORM attribute has been assigned so as to prevent updating (including erasing and changing) thereof for a given period of time.
Under the obligation to store the data, however, a data storage period may exceed a life of the storage system. In such a case, movement (migration) of data stored in an old storage system to a new storage system is necessary.
Additionally, there has recently been emerged an idea of Data LifeCycle Management (DLCM) for managing data throughout its lifetime from creation to erasure. According to the DLCM, when a value of data changes over time, it is advisable to move the data to a storage system of costs corresponding to the value.
However, when a computer system that includes the storage system is stopped for data migration, business is brought to a halt for this period to cause economic losses. Thus, there has been proposed a storage system equipped with a function of moving data without any system stoppage (e.g., JP 2003-108315 A).